static public bool IsInsideCurve(Curve cur, Point3d testPt)
{
if (!cur.Closed)
{
// Cannot be inside
return(false);
}
var poly2d = cur as Polyline2d;
if (poly2d != null && poly2d.PolyType != Poly2dType.SimplePoly)
{
// Not supported
return(false);
}
var ptOnCurve = cur.GetClosestPointTo(testPt, false);
if (Tolerance.Equals(testPt, ptOnCurve))
{
return(true);
}
// Check it's planar
var plane = cur.GetPlane();
if (!cur.IsPlanar)
{
return(false);
}
// Make the test ray from the plane
var normal = plane.Normal;
var testVector = normal.GetPerpendicularVector();
var ray = new Ray {
BasePoint = testPt, UnitDir = testVector
};
var intersectionPoints = new Point3dCollection();
// Fire the ray at the curve
cur.IntersectWith(ray, Intersect.OnBothOperands, intersectionPoints, 0, 0);
ray.Dispose();
int numberOfInters = intersectionPoints.Count;
if (numberOfInters == 0)
{
// Must be outside
return(false);
}
int nGlancingHits = 0;
const double epsilon = 2e-6; // (trust me on this)
for (int i = 0; i < numberOfInters; i++)
{
// Get the first point, and get its parameter
Point3d hitPt = intersectionPoints[i];
double hitParam = cur.GetParameterAtPoint(hitPt);
double inParam = hitParam - epsilon;
double outParam = hitParam + epsilon;
IncidenceType inIncidence = CurveIncidence(cur, inParam, testVector, normal);
IncidenceType outIncidence = CurveIncidence(cur, outParam, testVector, normal);
if ((inIncidence == IncidenceType.ToRight && outIncidence == IncidenceType.ToLeft) ||
(inIncidence == IncidenceType.ToLeft &&
outIncidence == IncidenceType.ToRight))
{
nGlancingHits++;
}
}
return((numberOfInters + nGlancingHits) % 2 == 1);
}
